Optical test platform

ABSTRACT

Provided herein are an optical test platform and corresponding method of manufacturing the same. The test platform may include a shell defining a cavity for receiving a sample tube, a first aperture, and a second aperture. The first aperture and the second aperture of the shell may each be configured to optically couple the cavity with an exterior of the shell. The test platform may further include a first window and a second window embedded in the shell. The first window may seal a first aperture and the second window may seal a second aperture. The first window and second window may each permit the optical coupling of the cavity with the exterior of the shell. The first window and the second window may be optically coupled via the cavity, and the shell may prohibit optical coupling between the first window and the second window through the shell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/815,585, filed Mar. 11, 2020, which is a continuation of U.S.application Ser. No. 15/958,771 (published as U.S. Publication No.2018/0306701), which is entitled “Optical Test Platform” and was filedApr. 20, 2018, which application claims the benefit of each of thefollowing: U.S. Provisional Application No. 62/487,807, which isentitled “Optical Test Platform” and was filed Apr. 20, 2017; U.S.Provisional Application No. 62/487,796, which is entitled “OpticalDensity Instrument And Systems And Methods Using The Same” and was filedApr. 20, 2017; U.S. Provisional Application No. 62/488,450, which isentitled “Optical Density Instrument And Systems And Methods Using TheSame” and was filed Apr. 21, 2017; U.S. Provisional Application No.62/487,860, which is entitled “Tip Resistant Optical Testing Instrument”and was filed Apr. 20, 2017; and U.S. Provisional Application No.62/487,736, which is entitled “Method, Apparatus, And Computer ProgramProduct For Controlling Components Of A Detection Device” and was filedApr. 20, 2017. Each of the foregoing applications is hereby incorporatedby reference in its entirety.

BACKGROUND

In microbiology laboratories and other similar settings, labtechnicians, scientists, and other practitioners use laboratoryequipment to measure conditions of liquid suspensions. The suspensionsmay be observed and manipulated in clear polystyrene test tubes, glasstest tubes, or other similar vials. The practitioner may utilize variousdevices or instruments to perform readings and measurements on theliquid in a tube. The practitioner may also manipulate the fluid whileperforming measurements, or intermittingly between measurements. In someexamples, a practitioner may manipulate the fluid while monitoring ameasurement or reading performed by an instrument.

One example of such a measurement performed in a microbiology labincludes measuring the turbidity and/or concentration of microorganismsin the liquid using an optical density instrument. The practitioner mayuse the instrument to achieve the optimal dilution of the sample bydiluting the solutions with saline, or increasing the levels ofmicroorganisms in the fluid. The optical density sensors in a device orinstrument may be configured to detect light emitted in the area of thetube to measure characteristics of the liquid.

Existing instruments are often incapable of being used continuouslyduring preparation of a sample because of poor visibility, interferencefrom external and internal light sources, leaks and other electricaldamage to the instrument's internal components, and high manufacturingcosts. The inventors have identified numerous other deficiencies withexisting technologies in the field, the remedies for which are thesubject of the embodiments described herein.

BRIEF SUMMARY

Provided herein are an optical test platform and associated systems andmethods. In some embodiments, the test platform may reduce interferenceat one or more sensors by reducing crosstalk and eliminating alternativelight paths other than the intended paths through a sample.

A test platform according to embodiments of the present disclosure maybe provided for facilitating the optical interrogation of a test sample.The test platform may include a shell defining a cavity for receiving asample tube, a first aperture, and a second aperture. In someembodiments, the first aperture and the second aperture each may beconfigured to optically couple the cavity with an exterior of the shell.The test platform may include a first window embedded in the shellacross the first aperture. The first window may seal the first aperture.The test platform may further include a second window embedded in theshell across the second aperture. The second window may seal the secondaperture. The first window and second window each may be configured topermit the optical coupling of the cavity with the exterior of theshell. The first window and the second window may be optically coupledvia the cavity, and the shell may be configured to prohibit opticalcoupling between the first window and the second window through theshell.

In some embodiments, the shell may be opaque, and in some furtherembodiments, the shell may be black.

The test platform may include a first mount for a first opticalcomponent and a second mount for a second optical component. The firstmount may be optically coupled with the first aperture at the exteriorof the shell, and the second mount may be optically coupled with thesecond aperture at the exterior of the shell. The first mount may beconfigured to position the first optical component to emit light intothe cavity through the first window along a first axis, and the secondmount may be configured to position the second optical component toreceive light from the cavity through the second window along a secondaxis. In some embodiments, the first axis and the second axis arecollinear, and in some other embodiments, the first axis and the secondaxis are not collinear. In some further embodiments, the first axis andthe second axis may be perpendicular.

In some embodiments, the shell may further include a third aperture, andthe test platform may further include a third window embedded in theshell. The third aperture may be configured to optically couple thecavity with the exterior of the shell, and the third window may seal thethird aperture. In some embodiments, the first window, the secondwindow, and the third window may be optically coupled via the cavity.The shell may be configured to prohibit optical coupling between thefirst window, the second window, and the third window through the shell.The third window may be offset from the first window and the secondwindow, such that the third window may be configured to receive aportion of light emitted through the first window along an axis betweenthe first window and the second window that is reflected within thecavity. In some embodiments, the first window and the second window eachmay be arranged on an axis that intersects a central axis of the cavity.The third window may be arranged on a second axis that is perpendicularto the axis of the first and second windows.

In some embodiments, at least one of the first window and the secondwindow may be molded into the shell of the test platform.

The test platform may further include a first mount positioned adjacentthe first aperture on an exterior of the shell. The first mount may beconfigured to receive a first optical component. In some embodiments,the first mount may include a first bore optically coupled with thefirst aperture and at least one attachment point, and the first mountmay be configured to allow the first optical component to attach to theattachment point and optically communicate with the cavity via the firstbore and the first aperture. In some embodiments, the first bore, thefirst aperture, and a first surface of the first window are orientedcoaxially along an axis extending through a central axis of the cavity,and the first mount may be configured to aim the first optical componenttowards the central axis along the axis.

In some embodiments, the test platform may further include a secondmount positioned adjacent the second aperture on an exterior of theshell, and the second mount may be configured to receive a secondoptical component. In some embodiments, the first mount may beconfigured to receive an emitter, and the second mount may be configuredto receive a sensor.

The shell may further define a second cavity configured to receive asecond sample tube.

In some embodiments, the test platform may include a spring defining afirst leg and a second leg. The spring may be configured to elasticallydeform to cause the first leg and the second leg to each apply a forceto a sample tube in a direction towards a point between the first legand the second leg. In some embodiment, at least one of the first legand the second leg may include rollers disposed thereabout, configuredto rotate about the respective leg to allow the sample tube to beinserted. In some embodiments, the shell may include one or more stopsand posts that retain the spring during, before, and/or after operation.

In another example embodiment, a method of manufacturing a test platformis provided. The test platform may include a shell defining a cavity forreceiving a sample tube, a first aperture, and a second aperture. Thefirst aperture and the second aperture each may be configured tooptically couple the cavity with an exterior of the shell. The testplatform may further include a first window embedded in the shell. Thefirst window may seal the first aperture. The test platform may includea second window embedded in the shell. The second window may seal thesecond aperture. The first window and second window each may beconfigured to permit the optical coupling of the cavity with theexterior of the shell. The first window and the second window may beoptically coupled via the cavity, and the shell may be configured toprohibit optical coupling between the first window and the second windowthrough the shell. The method may include embedding the first window andthe second window in the shell.

In some embodiments, embedding the first window and the second window inthe shell may include positioning the first window and the second windowin a shell mold, and molding the shell around the first window and thesecond window, such that the first window and the second window areembedded in the shell. The step of molding the shell around the firstwindow and the second window may include molding an opaque materialaround the first window and the second window.

In some embodiments, molding the shell around the first window and thesecond window may include permanently affixing the first window and thesecond window to the shell without adhesives or fasteners.

In some further embodiments, molding the shell may include molding afirst mount for a first optical component and a second mount for asecond optical component. The first mount may be optically coupled withthe first aperture at the exterior of the shell. The second mount may beoptically coupled with the second aperture at the exterior of the shell.The first mount may be configured to position the first opticalcomponent to emit light into the cavity through the first window along afirst axis, and the second mount may be configured to position thesecond optical component to receive light from the cavity through thesecond window along a second axis. In some embodiments, the first axisand the second axis may be collinear. In some other embodiments, thefirst axis and the second axis may not be collinear. In some furtherembodiments, the first axis and the second axis may be perpendicular.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the disclosure in general terms, reference willnow be made to the accompanying drawings, which are drawn to scaleexcept as noted otherwise, and wherein:

FIG. 1 is a perspective view of an instrument according to an exampleembodiment;

FIG. 2 is a not-to-scale illustration of the relative positioning of theoptical density emitters and sensors relative to the sample tubeaccording to an example embodiment;

FIG. 3 is a perspective view of an optical test platform according to anexample embodiment;

FIG. 4 shows the optical paths of light traveling through the opticaltest platform of FIGS. 2 and 3;

FIG. 5 is a top plan view of the optical test platform according to anexample embodiment;

FIG. 6 is a bottom plan view of the optical test platform according toan example embodiment;

FIG. 7 is a side view of the optical test platform according to anexample embodiment;

FIG. 7A is a detail view of the mount shown in FIG. 7;

FIG. 8 is another side view of the optical test platform according to anexample embodiment;

FIG. 8A is a detail view of the mount shown in FIG. 8;

FIG. 9 is another side view of the optical test platform according to anexample embodiment;

FIG. 9A is a detail view of the mount shown in FIG. 9;

FIG. 10 is another side view of the optical test platform according toan example embodiment;

FIG. 11 is another side view of the optical test platform according toan example embodiment;

FIG. 12 is a cross-section taken across reference orientation A-A shownin FIG. 5;

FIG. 13 is a cross-section taken across reference orientation B-B shownin FIG. 5;

FIG. 14 is a cross-section taken across reference orientation C-C shownin FIG. 5;

FIG. 15 is a window according to an example embodiment;

FIG. 16 is a lower window according to an example embodiment;

FIG. 17 is a top plan view of an optical test platform according to anexample embodiment;

FIG. 18 is a not-to-scale simplified top plan view of an optical testplatform according to an example embodiment;

FIG. 19 is a perspective view of a spring with rollers according to anexample embodiment;

FIG. 20 is a top plan view of an optical test platform according to anexample embodiment;

FIG. 21 is a bottom plan view of a housing for an optical densityinstrument according to an example embodiment;

FIG. 22 is a perspective view of the optical test platform of FIG. 20;

FIG. 23 is a cross section of the optical test platform of FIG. 20;

FIG. 24 is a bottom plan view of the optical test platform of FIG. 20;

FIG. 25 is a side view of the optical test platform of FIG. 20;

FIG. 26 is a window according to an example embodiment;

FIG. 27 is a top plan view of a lower window according to an exampleembodiment; and

FIG. 28 is a cross section of the lower window of FIG. 27.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings in which some but not allembodiments of the inventions are shown. Indeed, these inventions may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

The instruments and accompanying methods and systems described hereinare directed to an improved optical test platform for an optical densityinstrument. As described herein, the optical test platform mayfacilitate optical interrogation of a sample by supporting andpositioning the sample in optical alignment with one or more opticalemitters and optical density sensors. In a preferred embodiment, aliquid sample may be held in a sample tube, and the tube may besupported and positioned by the optical test platform to facilitate theinterrogation. One readout for this measurement of turbidity and/orconcentration of microorganisms in the liquid that can be obtained isknown as a McFarland value. This value is obtained using a series ofMcFarland standards, which are a series of known concentrations ofsolutions that are used to prepare a standard curve in order todetermine the concentration of particles in an unknown sample.

FIG. 1 shows an example optical density instrument in accordance withthe present invention. In the depicted embodiment, the opticalinstrument 1 holds two sample tubes 15 for optical density testing. Theoptical instrument 1 may comprise a handheld unit 10 and a base station20. In some embodiments, the handheld unit is battery operated forconvenience and flexibility and includes the optical test platformdetailed herein. The handheld unit 10 may transmit data to the basestation 20 via Bluetooth® or another wireless or wired protocol thatpermits real time data transfer. The base station 20 may then be wire orwirelessly connected to a computer for receiving the optical densitydata in real time. In some embodiments, the handheld unit 10 may holdtwo sample tubes or a fused, dual sample tube 15. Further detailsregarding the instrument, its structure, and operation may be found inU.S. Provisional Application No. 62/487,796, entitled “OPTICAL DENSITYINSTRUMENT AND SYSTEMS AND METHODS USING THE SAME,” which application isincorporated by reference herein in its entirety.

With reference to FIG. 2, an illustration of the optical components 22,24, 26, 28 and a sample tube 15 of the optical density instrument areshown. The optical density components may include at least one emitter22 (e.g., an LED, photodiode, or other light source) for emitting lightinto the sample tube 15 and at least one sensor 24, 26 (e.g., aphotodetector, CCD, CMOS, or any other sensor capable of receivingincident light and outputting a signal indicative of the light'sintensity) for receiving light that passes through the sample. In theillustrated embodiment of FIG. 2, one emitter 22 and two sensors 24, 26are used to generate an accurate optical density reading of the sample.In operation, the emitter 22 may transmit light into the sample and aportion of the transmitted light passes through the sample to a firstsensor 24 positioned opposite the emitter 22 relative to the sample tubeand oriented collinearly with the emitter, while a second portion of thetransmitted light reflects off of the sample and is collected by asecond sensor 26 offset from the axis spanning the emitter 22 and firstsensor 24.

In particular, the first sensor 24 may be oriented collinearly relativeto the axis 30 of the emitter 22 and may be oriented 180 degrees offsetfrom the emitter 22 with respect to the axis 32 of the sample tube 15.In some embodiments, the second sensor 26 may be positioned 90 degreesabout the radial circumference of the sample tube 15 from both theemitter 22 and first sensor 24 on a perpendicular axis 34 to collectreflected light. In some embodiments, the second sensor 26 may bepositioned at an acute angle to the axis 30 of the emitter 22. In someother embodiments, the second sensor 26 may be positioned at an obliqueangle to the axis 30 of the emitter 22. In some embodiments, aperpendicularly-oriented nephelometric sensor may

The emitter 22 may be configured to transmit the light perpendicular tothe surface of the tube 15 and, in some embodiments, perpendicular tothe longitudinal axis 32 of the sample tube 15. The portion of lightcollected by the first, pass-through sensor 24 may be called the“density” reading, and the portion of light collected by the second,reflective sensor 26 may be called the “nephelometric” reading. Theoptical density instrument may then combine the density andnephelometric signals from each sensor 24, 26 to generate a McFarlandreading (or other optical measurement) of the sample. Further detailsregarding the operation of the sensors, including calibration, zeroing,and data collection, may be found in U.S. Provisional Application No.62/487,736, entitled “METHOD, APPARATUS, AND COMPUTER PROGRAM PRODUCTFOR CONTROLLING COMPONENTS OF A DETECTION DEVICE,” which application isincorporated by reference herein in its entirety.

With continued reference to FIG. 2, in some embodiments, a practitionermay wish to observe the sample directly during optical testing. In suchembodiments, the optical components may further include an illuminationlight 28 (e.g., an LED or other light source) configured to emit lightupwardly into the sample. Further details regarding the operation of theillumination light, and corresponding methods of using and reducinginterference from the illumination light, may be found in U.S.Provisional Application No. 62/487,736, entitled “METHOD, APPARATUS, ANDCOMPUTER PROGRAM PRODUCT FOR CONTROLLING COMPONENTS OF A DETECTIONDEVICE,” which application is incorporated by reference herein in itsentirety.

With reference to FIGS. 3-14, the instrument includes the optical testplatform 100 to structurally support and align each of the opticalcomponents 22, 24, 26, 28 with the sample tube 15. Existing opticaldensity instruments suffer from a number of deficiencies with respect tothe alignment, support, and operation of their traditional opticalelements. For example, it is preferred to seal the sample support areaof the optical test platform from the electronics to avoid spillageissues, and thus, the optical test platform 100 positions the opticalcomponents 22, 24, 26, 28 outside of the sample tube 15 support area(e.g., cavity 112 a shown in FIG. 3). This then requires the opticalcomponents 22, 24, 26, 28 to be able to optically communicate throughthe shell of the optical test platform. If the entire optical testplatform 100 is molded as a single piece, the piece must be at leastpartially transparent to allow the light to propagate through theplatform and sample. If, however, the entry point for the lighttransmitted by the emitter 22 into the optical test platform 100 isallowed to optically communicate through a shell 110 of the instrumentwith the exit point of the light received by either sensor 24, 26, theaccuracy of the instrument may deteriorate. Said differently, if thestructure of the optical test platform 100 allows light to travel fromthe emitter 22 to one or both of the sensors 24, 26 without passingthrough the sample 15, interference may negatively affect the testresults.

FIGS. 3-14 show various views of an example optical test platform 100.With reference to FIG. 3, a perspective view of the optical testplatform 100 is shown in accordance with embodiments detailed herein.The optical test platform 100 of the present disclosure may includeseparate windows 102, 104, 106, 108 located within and embedded into theshell 110 of the test platform.

The shell 110 may be molded of an opaque or semi-opaque material. Insome further embodiments, the shell 110 may be formed of a dark colorpolymer. In yet some further embodiments, the shell 110 may be formed ofa black polymer. The windows 102, 104, 106 allow light to pass throughthe shell 110 at generally perpendicular angles to the surface of thewindow, with the shell material prohibiting light from propagatingthrough the shell itself. The shell 110 may define one or more cavities112 a, 112 b (collectively “112”) therein. The cavities 112 may receivethe sample tubes 15 (shown in FIGS. 1-2) through an upper aperture 114a, 114 b (collectively “114”), and the sample tubes 15 may be supportedby the shell. In some embodiments, the cavities 112 may be substantiallycylindrical, and in some embodiments, the cavities 112 may be bounded byone or more walls 116 a, 116 b.

The shell 110 may hold any of several configurations of sample tubes 15.For example, in the depicted embodiment of FIG. 3, the shell 110includes two cavities 112 a, 112 b configured to receive twocorresponding sample tubes 15. The depicted embodiment is configured totest one of the two tubes (e.g., the optical components only interrogateone of the two cavities, cavity 112 a), while the second cavity 112 b isleft for convenience to hold a second tube. For example, once theoptical density of the tube 15 in the first cavity 12 a reaches adesired concentration, separate samples based on that concentration maybe made in the second tube 15 (e.g., diluted versions of the originalconcentration based on the known concentration of the tube in the firstcavity 112 a, such as for antibiotic susceptibility testing). This dualsample tube configuration is useful for use with a dual-test tube orother fused sample tubes, where the two tubes should be kept togetherfor study but need not be independently checked with optical densitysensors. In some alternative embodiments, two or more optical componentsmay be used to interrogate the second cavity 112 b. Although thedescription herein refers to interrogating a single sample tube, theseteachings may be readily applied to a second set of optical componentsoperating on the second cavity 112 b. In some alternative embodiments,the optical test platform may include only a single cavity for testing asingle sample tube, or in some embodiments, greater than two sampletubes may be used with one, two, or more sets of optical components forinterrogating the respective tubes. The cavities 112 may include asupport ring 146 or fillet for engaging and supporting the sample tubes15.

The optical test platform 100 may include one or more mounts 120, 122,124 for engaging and supporting the optical components (e.g., theemitter 22, first sensor 24, second sensor 26, and/or illumination light28 shown in FIG. 2). In the embodiments shown in FIGS. 2-14, the firstmount 120 may receive and engage the emitter 22, the second mount 122may receive and engage the second sensor 26, and the third mount mayreceive and engage the first sensor 24. One of ordinary skill in the artwill also appreciate, in light of this disclosure, that the mounts 120,122, 124 and optical components 22, 24, 26, 28 may be reconfigured toany arrangement that satisfies the possible emitter-sensor relationshipsdiscussed herein. In some embodiments, the mounts 120, 122, 124 may beintegrally molded with the shell 110, and in some other embodiments, themounts 120, 122, 124 may be separately attached to the shell.

FIGS. 7-7A show side views of the first mount 120 viewed from theexterior of the optical test platform, and FIG. 13 (left side) shows across-sectional view of the first mount 120. FIGS. 9-9A show side viewsof the second mount 122 viewed from the exterior of the optical testplatform, and FIG. 14 shows a cross-sectional view of the second mount122. FIGS. 8-8A show side views of the third mount 124 viewed from theexterior of the optical test platform, and FIG. 13 (right side) shows across-sectional view of the third mount 124.

With reference to the respective figures in the aforementionedparagraph, each of the mounts 120, 122, 124 may include a central bore138 into which a portion of the optical receiving or transmittingelements of the respective optical components 22, 24, 26, 28 (shown inFIG. 2) may be inserted. At a distal end of the central bore 138,opposite the cavity 112 a, each mount 120, 122, 124 may define a notch140 for receiving a portion of the optical components therein. The notch140 may further define a keyway 142 for rotationally aligning theoptical component with in a respective bore 138, by engaging acorresponding notch in the optical component.

At a proximate end of the central bore 138 of each mount 120, 122, 124,the shell 110 may define an aperture 130 to allow light to pass throughthe shell. The aperture 130 may optically connect the cavity 112 a withthe optical components 120, 122, 124 to allow the optical components torespectively transmit light into the cavity from outside the cavity, orreceive light outside the cavity from inside the cavity. In someembodiments, the aperture 130 may have a narrower diameter than thecentral bore 138, which may assist with positioning the opticalcomponents by providing a predefined stop point for the components, mayreduce interference or noise from being received by the sensors 24, 26by narrowing the opening through which light passes into the opticalcomponent, and may structurally support the window 102, 104, 106 bypreventing the optical component from acting on the window.

The shell may further define an aperture 130 at a lower end of thecavity 112 a opposite the upper aperture 114 a. In some embodiments, awindow 108 may be embedded in the aperture 130 to allow the illuminationlight 28 (shown in FIG. 2) or another optical component to communicatewith the cavity. In the embodiment depicted in FIGS. 3-14, the lowerwindow 108 may allow the illumination light 28 (shown in FIG. 2) toilluminate the sample tube 15 (shown in FIG. 2).

The windows 102, 104, 106, 108 may be embedded in the shell 110 to allowoptical communication between outside the cavity 112 a, including theinterior of the bore 138, and the interior of the cavity 112 a via theaperture 130. As used herein, the term “embedded” refers to thepermanent (at least requiring damage, plastic deformation, and/ordestruction) affixation between the window and shell without requiring(although not precluding) adhesives, such that the physical structure ofthe shell retains the window. In some embodiments, no adhesives orfasteners may be used to embed the windows 102, 104, 106, and 108 withinthe shell 110. In some embodiments, the windows 102, 104, 106, 108 areembedded into the shell 110 by molding the shell around the windows tofix them within the permanently-molded structure of the shell. One ofordinary skill in the art will appreciate, in light of the presentdisclosure, that the shell 110 may be made of one or several pieces,which may be molded together or attached separately without departingfrom the scope of the present disclosure. For example, in some otherembodiments, the shell may be machined or 3D printed and shaped orsnapped around the windows.

In some embodiments, the aperture and window for each respective opticalcomponent may be generally coplanar, such that the window is positionedwithin the aperture (e.g., as shown in FIGS. 12-14 between the aperture130 and lower window 108). In some other embodiments, as shown in FIGS.12-14, the window may rest axially against the aperture in a separatepocket (e.g., as shown in FIGS. 12-14 between the aperture 130 andsensory windows 102, 104, 106). In any embodiment, the embedding processmay seal the window 102, 104, 106 and shell 110 such that fluid may notpass through the aperture 130 and damage the electronics of theinstrument. In some embodiments, a rib or flange of the shell 110 mayoverlap the window about its edges to encapsulate the edges of thewindow and provide a seal and fixation. With reference to FIGS. 15 and16, diagrams of the sensory windows 102, 104, 106 and the lower window108 are shown respectively. In some embodiments, with reference to FIG.15, the sensory windows 102, 104, 106 may be substantially rectangular,with a longer vertical dimension than horizontal dimension. The sensorywindows 102, 104, 106 may include notches 144 for improving fixationbetween the shell 110 and windows.

Referring back to FIGS. 3-14, each of the mounts 120, 122, 124 mayinclude one or more attachment points 136 to which the opticalcomponents may be attached. For example, FIGS. 7-7A show attachmentpoints 136 (e.g., screw or bolt holes) of the first mount 120 to whichthe emitter 22, or one of the sensors 24, 26 (shown in FIG. 2) may bemounted. Similarly, FIGS. 9-9A show attachment points 136 (e.g., screwor bolt holes) of the second mount 122 to which the emitter 22, or oneof the sensors 24, 26 (shown in FIG. 2) may be mounted. Further, FIGS.8-8A show attachment points 136 (e.g., screw or bolt holes) of thesecond mount 122 to which the emitter 22, or one of the sensors 24, 26(shown in FIG. 2) may be mounted. In some embodiments, the attachmentpoints 136 may be on opposite sides of the bore 138 of the mounts 120,122, 124.

The mounts 120, 122, 124; the central bores 138; the apertures 130; andthe sensory windows 102, 104, 106 may each be configured to facilitatethe operation of the emitters and/or sensors described herein. In someembodiments, the mounts 120, 122, 124; the central bores 138; theapertures 130; and/or the sensory windows 102, 104, 106 may be orientedco-axially with the respective emitters or sensors affixed thereto. Forexample, first mount 120 shown in FIG. 3 may engage the emitter 22 shownin FIG. 2, and in such case, the first mount 120 (including bore 138 andnotch 140), the corresponding aperture 130, and the first window 102 mayeach be oriented along the axis 30 of the emitter 22 shown in FIG. 2. Insuch embodiments, the bore 138 and aperture 130 may be cylindrical andmay have a longitudinal axis that is coaxial with the axis 30 of theemitter 22. Similarly, the first window 102 may have a surface whosenormal vector is aligned with the axis 30 of the emitter 22, such thatlight may pass into the window in a generally perpendicular direction toreduce distortion.

Similarly, the shell 110 may include a mount for the illumination light28, which may also align the illumination light 28 with the componentsof the mount and the window 108. The illumination light 28 may therebyilluminate the sample tubes 15 for observation by the practitioner. Inthe embodiment shown in FIG. 3, the illumination light 28 (shown in FIG.2) may be oriented upwardly into the cavity 112 a to illuminate thesample tube 15 (shown in FIG. 2) from beneath. The illumination light 28may be oriented perpendicular to the axes of the emitter 22, firstsensor 24, and/or second sensor 26. For example, with reference to FIG.2, the illumination light 28 is oriented along the central axis 32 ofthe sample tube 15.

The aforementioned alignment may also be provided with respect to thefirst sensor 24 and the third mount 124 and corresponding aperture 130,and with respect to the second sensor 26 and the second mount 122 andcorresponding aperture 130. For example, the bore 138 and aperture 130associated with the third mount 124 may be cylindrical and may have alongitudinal axis that is coaxial with the axis 30 of the emitter 22(also corresponding to the axis of the first sensor 24 based on theircollinearity). The third window 106 may also have a surface whose normalvector is aligned with the axis 30 of the emitter 22, such that lightmay pass into the window in a generally perpendicular direction toreduce distortion. Moreover, the bore 138 and aperture 130 associatedwith the second mount 122 may be cylindrical and may have a longitudinalaxis that is coaxial with the axis 34 of the second sensor 26. Thesecond window 104 may also have a surface that is perpendicular to theaxis 34 of the second sensor 26, such that light may pass into thewindow in a generally perpendicular direction to reduce distortion. Asdiscussed above, the axis 30 of the emitter 22 and first sensor 24 maybe collinear and each may be offset from and, in some embodiments,perpendicular to the axis 34 of the second sensor 26. As also discussedabove, the emitter 22 and sensors 24, 26 may be attached to anycombination of mounts 120, 122, 124 that facilitates either densitysensing (e.g., collinear placement of the emitter and sensor),nephelometric sensing (e.g., offset placement of the emitter andsensor), or both. For example, the emitter 22 may be attached to thethird mount 124, with the first sensor 24 being attached to the firstmount 120 and the second sensor 26 being attached to the second mount122.

With reference to FIG. 4, an illustration of the optical coupling of theemitters and sensors is shown. In the depicted embodiment of FIG. 4, theemitter 22 (shown in FIG. 2) would be attached to the first mount 120,the first sensor 24 (shown in FIG. 2) would be attached to the thirdmount 124, and the second sensor 26 (shown in FIG. 2) would be attachedto the second mount 122. In operation, the emitter 22 may emit light 150into the cavity 112 a. A first portion of the light 152 may be reflectedfrom the sample in the cavity 112 a and received by the nephelometricsecond sensor 26, and a second portion of the light 154 may pass throughthe sample in the cavity 112a and be received by the density firstsensor 24. In the depicted embodiment, the first window 102, first mount120, third window 106, and third mount 124 are arranged collinearly, andthe second window 104 and second mount 122 are perpendicular to the axisof the first window 102, first mount 120, third window 106, and thirdmount 124. Thus, in the depicted embodiment, the emitter 22 and firstsensor 24 would be arranged collinearly, and the second sensor 26 wouldbe arranged perpendicular to the emitter 22 and first sensor 24.

Although the nephelometric 152 and density 154 signals are showndiverging at the center of the sample, the reflection and dispersion ofthe emitted light 150 may gradually occur across the length of thecavity 112 a assuming an equal distribution of the sample.

As used herein, the term “optical coupling” or “optically coupled”refers to two components or features between which light may travel. Insome instances, one or more features, such as the windows 102, 104, 106,and 108 and the apertures 130 may facilitate optical coupling byallowing light to pass therethrough.

The windows 102, 104, 106, and 108 described herein may be made of anytransparent or substantially transparent material, including glass orpolymers. For example, in some embodiments, the windows 102, 104, 106,and 108 may be made of Lexan®. In some embodiments, the shell 110 may bemade of polypropylene, polyphenylene ether (PPE) resin, polypropyleneoxide (PPO), polystyrene, or blends thereof. For example, in someembodiments, the shell 110 may be made of Noryl®. In some embodiments,the windows 102, 104, 106, and 108 may be made of any optically clearmaterial. The shell 110 may either be molded of an opaque material, orthe shell material may be dyed (e.g., black) to prevent opticaltransmission through the shell's structure. In some embodiments, theshell 110 may be made of any material that blocks light. In some furtherembodiments, the shell 110 may be made of any moldable material thatblocks light.

Referring back to FIG. 3, in some embodiments, the shell 110 may have aslot 200 configured to receive a switch therein. The switch may detectplacement of the sample tube 15 in the cavity 112 a to trigger theoptical density measurements and/or illumination steps detailed herein.The switch may be a mechanical switch that includes an actuator armprotruding into the cavity 112 a from the slot 200 to contact the sampletubes 15 when they are nearly completely inserted. In some embodiments,the switch may be an electromechanical switch whose lever arm deflectsinto an electrical contact for signaling the optical testing instrumentto automatically begin interrogating the sample.

In some embodiments, a method of manufacturing the test platform 100described herein may be provided. With reference to FIG. 3, the testplatform 100 may include a shell 110 defining a cavity 112 a forreceiving a sample tube 15, a first aperture 130, and a second aperture130. The first aperture 130 and the second aperture 130 may each beconfigured to optically couple the cavity 112 a with an exterior of theshell. The test platform 100 may further include a first window 102embedded in the shell 110. The first window 102 may seal the firstaperture 130. Moreover, a second window 104, 106 may be embedded in theshell 110, wherein the second window 104, 106 may seal the secondaperture 130. The first window 102 and the second window 104, 106 mayeach be configured to permit the optical coupling of the cavity 112 awith the exterior of the shell. The first window 102 and the secondwindow 104, 106 may be optically coupled via the cavity 112 a, and theshell 110 may be configured to prohibit optical coupling between thefirst window 102 and the second window 104, 106 through the shell 110.

The method may include embedding the first window and the second windowin the shell. In some embodiments, embedding the first window and thesecond window in the shell may include positioning the first window andthe second window in a shell mold, and molding the shell around thefirst window and the second window, such that the first window and thesecond window may be embedded in the shell. In some embodiments, moldingthe shell around the first window and the second window may includemolding an opaque material around the first window and the secondwindow. In some further embodiments, molding the shell around the firstwindow and the second window may include permanently affixing the firstwindow and the second window to the shell without adhesives orfasteners.

In some embodiments, molding the shell may further include molding afirst mount 120 for a first optical component and a second mount 122,124 for a second optical component. The first mount 120 may be opticallycoupled with the first aperture 130 at the exterior of the shell 110.The second mount 122, 124 may be optically coupled with the secondaperture 130 at the exterior of the shell 110. The first mount 120 maybe configured to position the first optical component 22 to emit lightinto the cavity 112 a through the first window 102 along a first axis30.

In some embodiments, a second mount 124 may be configured to positionthe second optical component 24 to receive light from the cavity 112 athrough the second window 106 along a second axis 30, and the first axisand the second axis may be collinear. This embodiment may be called adensity sensor and mount.

In some other embodiments, a second mount 122 may be configured toposition the second optical component 26 to receive light from thecavity 112 a through the second window 104 along a second axis 34, andthe first axis and the second axis may not be collinear. This embodimentmay be called a nephelometric sensor and mount.

Turning to FIG. 17, a second embodiment of the optical test platform 300is shown. The optical test platform 300 may include a shell 310 with oneor more mounts 320, 322, 324; an aperture 330; upper apertures 314 a,314 b; and cavities 312 a, 312 b that may each be structured and operatein substantially the same manner as the example optical test platforms100, 800 detailed herein. Moreover, embodiments of the optical testplatform 300, or portions thereof, may be incorporated into orsubstituted for portions of the optical test platforms 100, 800 detailedherein.

With continued reference to FIG. 17, the optical test platform 300 mayinclude at least one spring 340 that urges a sample tube 342 to apredetermined position within one or more of the cavities 312 a, 312 b.In the embodiment depicted in FIG. 17, the optical test platform 300includes a spring 340 configured to bias a sample tube 342 towards awindow 106. The depicted spring 340 includes a coiled wire 344 disposedaround a post 346 and two legs 348, 349 defining the respective ends ofthe wire.

The spring 340 may operate as a helical torsion spring, such that thehelical coiled wire 344 is twisted about the axis of the coil (e.g., anaxis extending perpendicular to the page of FIG. 17) by bending momentsapplied at the legs 348, 349. In such embodiments, the coiled wire 344may elastically deform in response to a force on either or both legs348, 349, and the coiled wire 344, when elastically deformed, may causethe legs 348, 349 to apply a force opposite the direction of the appliedforce. For example, the sample tube 342 may be inserted into the cavity312 a between the two legs 348, 349 which may cause an outward force(e.g., a force radially outward from the center of the cavity 312 a) onthe legs 348, 349 and a torsional torque on the coiled wire 344. Thelegs 348, 349 may apply an opposing inward force (e.g., a force radiallyinward towards the center of the cavity 312 a) on the sample tube 342,caused by the torsional reaction torque of the coiled wire 344, whichmay push the sample tube toward the window 106.

In the depicted embodiment, the post 346 and spring 340 are disposed atthe same side of the cavity 312 a as the first mount 320, opposite thethird window 106, to cause the spring to urge the sample tube 342towards the third window as described herein. In some embodiments, thepost 346 and spring 340 may be disposed at any other side of the cavity,including opposite the second window 104.

In some embodiments, a roller 354, 355 may be disposed on each of therespective legs 348, 349 of the spring 350, and the rollers 354, 355 maybe slip fit or otherwise allowed to rotate about the legs 348, 349 toallow the sample tube 342 to move freely upwardly and downwardly (e.g.,into and out of the page of FIG. 17). The legs 348, 349 may apply forcesto the sample tube 342 perpendicular to the surfaces of the rollers 354,355 (e.g., a force vector substantially intersecting a center ofrotation of the rollers), while the rollers rotate when force is appliedtangential to the surface of their surface. In this manner, gravity mayretain the sample tube 342 vertically within the cavity 312 a whilestill allowing the sample tube to be freely removed or inserted, and inthe depicted embodiment, the spring 340 may hold at least a portion ofthe sample tube in position within the horizontal plane (e.g., the planeof the paper in FIG. 17). In some embodiments, the rollers 354, 355 maycause the legs 348, 349 to each apply a purely horizontal force to thesample tube 342. In some embodiments, the rollers 354, 355 may definegenerally hollow cylinders disposed about the legs 348, 349. In someembodiments, the rollers 354, 355 may be made from a low-frictionmaterial to prevent scratching the sample tube 342. For example, in someembodiments, the rollers 354, 355 may be made of PEEK (Polyether etherketone), PTFE (Polytetrafluoroethylene), or Acetal (Polyoxymethylene).

With reference to FIG. 18, a simplified embodiment of the spring 340,sample tube 342, and surrounding components are shown for illustrationpurposes. In the depicted embodiment, the legs 348, 349 may apply forces364, 366 on the sample tube 342 in directions that are at leastpartially towards a detector 362 and at least partially towards a centeraxis 360 bisecting the legs 348, 349. In some embodiments, the centeraxis 360 may extend between a diametric center of the post 346 and thedetector 362. In some embodiments, the widthwise center of one or morewindows (e.g., windows 102 and 106 shown in FIG. 5) may be defined onthe center axis 360. Although not shown in FIG. 18, a window (e.g.,window 106 shown in FIGS. 5 and 17) may be positioned between the sampletube 342 and the detector 362.

The cavity 312 a may be bounded by a wall 316 a of the optical testplatform. In some embodiments, two or more alignment ribs 352, 353 maybe disposed on the wall 316 a of the cavity 312 a to help position thesample tube 342 along the center axis 360. In some embodiments, the ribs352, 353 may be molded as part of the shell 310. In the embodimentdepicted in FIG. 18, the alignment ribs 352, 353 may hold the sampletube 342 in a predetermined position (e.g., the position shown in FIGS.17 and 18) when the legs 348, 349 apply a force in any direction havinga force component towards the detector 362. In this manner, thealignment ribs 352, 353 may provide a stable, repeatable position forthe sample tube 342 without requiring a precise force vector from thelegs 348, 349, and the ribs 352, 353 may guide the sample tube 342 intoposition, for example, to a position centered along the center axis 360.In some embodiments, the legs 348, 349 may be configured to apply aforce to the sample tube 342 towards a point between the legs (e.g., anintersection point of the force vectors 364, 366), with the coiled wire344 attempting to move the legs 348, 349 in counter-rotating directionsabout the axis of the helical spring.

The predetermined position of the sample tube 342 may be designed tofacilitate a clear, repeatable interrogation of the sample tube usingthe techniques and apparatus described herein, and the predeterminedposition may be dependent on the diameter of the sample tube and thespacing between the ribs. In some embodiments, the ribs 352, 353 may bepositioned at least at a vertical position of one of the legs 348, 349.In some embodiments, the ribs 352, 353 may be positioned below avertical position of the legs 348, 349. In some embodiments, the ribs352, 353 may be positioned between the vertical positions of the legs348, 349. In some embodiments, the ribs 352, 353 may be positioned atthe vertical position of both legs 348, 349. In some embodiments, thelegs 348, 349 may disposed on or may apply a force in a horizontalplane, such that the line of action of the spring is on a horizontalplane relative to the optical test platform 300. In some embodiments,the ribs 352, 353 may extend substantially the height of the cavity 312a.

In operation, the sample tube 342 is inserted into the cavity 312 a ofthe optical test platform 310 (shown in FIG. 17). As the sample tube 342is inserted, the legs 348, 349 are pushed away from the center axis 360as the rollers 354, 355 allow the sample tube to slide into the cavity312 a. The torque created by the elastic deformation of the coiled wire344 of the spring 340 may cause each leg 348, 349 to apply a force 364,366 on the sample tube 342. Each of the forces 364, 366 of the legs 348,349 may be in a direction that is at least partially towards the centeraxis 360 and at least partially towards the detector 362.

In some embodiments, the components of the forces 364, 366 that areperpendicular to the center axis 360 may cancel, leaving a net force onthe sample tube 342 along the center axis 360 towards the detector 362.The spring 340 may apply a reaction force on the post 346 at a pointclosest to the detector 362 on the center axis 360. In some embodiments,as described below, the legs 348, 349 may be vertically offset such thatthere is a slight torque applied to the sample tube 342, and this torquemay be counteracted by the structure of the optical test platform (e.g.,the ribs 352, 353 and/or guide surface 368). The sample tube 342 may beheld vertically within the cavity 312 a between the various contactpoints described herein.

With reference back to FIG. 4, in some embodiments, the spring 340(shown in FIGS. 17-19) and alignment structures 352, 353, 368 may beconfigured to position the sample tube 342 (shown in FIGS. 17-18)adjacent the third window 106 such that the density signal 154 isincident upon the sample tube 342 and window 106 perpendicular to theirrespective surfaces. In such embodiments, the spring 340 may bepositioned opposite the window 106 as shown in FIG. 17. In suchembodiments, the emitted light 150 may also be incident upon the sampletube perpendicular to its surface, and the emitted light 150 and densitysignal 154 may travel at least partially along the center axis 360 shownin FIG. 18 (e.g., the detector 362 may receive the density signal 154).In some embodiments, the spring 340 may position the sample tube 342closer to the third window 106 than to the first window 102 or secondwindow 104, such that in some embodiments the surface of the sample tubemay not align with the second window 104 to transmit the nephelometricsignal 152 perpendicularly through both surfaces. As detailed herein, insome embodiments, the spring 340 may be configured to position thesample tube adjacent any of the first, second, or third windows, withthe alignment ribs on either side of any of the aforementioned windowsand the spring opposite any of the aforementioned windows.

When no sample tube 342 is inserted in the cavity 312 a, the legs 348,349 of the spring 340 may engage respective stops 350, 351 on theoptical test instrument 310 (shown in FIG. 17). In some embodiments, thestops 350, 351 may be positioned equidistant from the center axis 360such that the legs 348, 349 remain centered relative to the axis 360 toreceive the sample tube 342 therebetween. In some embodiments, the stops350, 351 may be configured to engage the legs 348, 349 such that thespring 340 is always elastically deformed when positioned on the post346. In such embodiments, spring 340 may apply a force to the stops 350,351 when not otherwise obstructed or resisted by the sample tube 342,and the continuous deformation may help create a smooth motion in thespring 340 without slop or slack in the motion or application of force.In some embodiments, the legs 348, 349 may be disposed perpendicular toeach other when the legs are engaged with the respective stops 350, 351.In some embodiments, the stops 350, 351 may be positioned such that thelegs 348, 349 and rollers 354, 355 protrude vertically over the cavity312a when no sample tube 342 is inserted. In some embodiments, the stops350, 351 may be positioned such that the legs 348, 349 and rollers 354,355 protrude less than half way over the cavity 312 a when no sampletube 342 is inserted. In some embodiments, the spring 340 may bepositioned between the shell 310 of the optical test platform and theouter housing of the instrument (shown in FIG. 1).

In some embodiments, the stops 350, 351 may be positioned such that,when a sample tube 342 is inserted into the cavity and is held againstthe ribs 352, 353, the legs 348, 349 comes into contact with the stops.In some embodiments, the sample tube 342 may prevent the legs 348, 349from contacting the stops 350, 351 when in the predetermined position.In some embodiments, the legs 348, 349 may apply a force (e.g., forces364, 366) to the sample tube 342 both before and while the sample tubeis in the predetermined position against the ribs 352, 353.

Turning to FIG. 19, a perspective view of an embodiment of the spring340 is shown. In the depicted embodiment, the legs 348, 349 cross eachother near the coiled portion of the wire 344. As shown in FIG. 18, thecross over may occur along the center axis 360. Outward force on thelegs 348, 349 away from the center axis 360 may cause the coiled wire344 to torsionally tighten and compress in the depicted embodiment.

Turning back to FIG. 19, the legs 348, 349 may be vertically separatedfrom each other due to the thickness of the spring 340 in the axis ofthe helical coil, which may cause one leg (e.g., the uppermost leg 349)to protrude over the cavity (e.g., cavity 312 a shown in FIGS. 17-18) ata higher position than another leg (e.g., lowermost leg 348). In suchembodiments, a torque may be applied to the sample tube 342 in adirection within the horizontal plane (e.g., the plane of the paper inFIGS. 17-18) attempting to move the sample tube out of verticalalignment, and the torque may be counteracted by the structures andguiding surfaces of the optical test platform described herein. In someembodiments, the legs may be bent or otherwise reoriented in anotherdirection while still being able to apply force to the sample tube.

With reference to FIG. 17, in some embodiments, the lower end of thecavity 312 a, proximate the lower window 108, may define a U-shapedguide surface 368 oriented with a curved portion 369 defining asemi-circle and a pair of straight portions 370 extending to either sideof a window 106. In the depicted embodiment, the curved portion 369 ofthe guide surface 368 is disposed on the same side of the cavity 312 aas the post 346 and majority of the spring 340 such that the force(e.g., forces 364, 366 shown in FIG. 18) of the spring 340 pushes thesample tube 342 along the U-shaped guide surface 368 towards thealignment ribs (e.g., alignment ribs 352, 353 shown in FIG. 18). TheU-shaped guide surface 368 may be disposed above the lower window 108,which window may function and be structures according to the embodimentsdescribed herein.

The sample tube 342 may engage the guide surface 368 and hold the sampletube upright and vertical against the alignment ribs (e.g., alignmentribs 352, 353 shown in FIG. 18). In some embodiments, the sample tube342 may have a curved, hemispherical bottom which may rest against acomplementarily angled surface of the guide surface 348. The curvedportion of the guide surface 368 may define a center of curvature thatis offset from the center of the lower window 108 and the center of thecavity 312 a, such that the sample tube is positioned closer to a window106 opposite the spring 340 and post 346 than to the windows 102, 104 onthe other surfaces of the wall 316 a of the cavity. The guide surface368 and alignment ribs 352, 353 may cooperate to hold the sample tube342 substantially vertically within the cavity 312 a and may cooperateto hold the sample tube parallel to the wall 316 a of the cavity. Thecurved portion 369 and straight portions 370 may provide a counteractingforce to the torque of the offset legs 348, 349 on the embodiment of thespring 340 and sample tube 342 described above.

Turning to FIGS. 20-28 another embodiment of the optical test platform800 is shown. The optical test platform 800 may include a shell 810 withone or more mounts 820, 822, 824; an aperture 830; upper apertures 814a, 814 b; and cavities 812 a, 812 b that may each be structured andoperate in substantially the same manner as the example optical testplatforms 100, 300 detailed above. Moreover, embodiments of the opticaltest platform 800, or portions thereof, may be incorporated into orsubstituted for portions of the optical test platforms 100, 300 detailedherein. In some embodiments, a first cavity 812 a may be used fortesting and/or operating on the fluid in a sample tube, while the secondcavity 812 b includes no testing windows or detectors.

With continued reference to FIG. 17, the optical test platform 800 mayinclude at least one spring 840 that urges a sample tube 842 to apredetermined position within one or more of the cavities 812 a, 812 b.The spring 840 may include rollers 854, 855 that operate insubstantially the same manner as the rollers 354, 355 detailed above. Inthe embodiment depicted in FIG. 17, the optical test platform 800includes a spring 840 configured to bias a sample tube 842 towards awindow 806. The depicted spring 840 includes a coiled wire 844 disposedaround a post 846 (shown in FIG. 21) and two legs 848, 849 defining therespective ends of the wire. The spring 840 may operate as a helicaltorsion spring, such that the helical coiled wire 844 is twisted aboutthe axis of the coil (e.g., an axis extending perpendicular to the pageof FIG. 17) by bending moments applied at the legs 848, 849.

With reference to FIG. 21, an example underside of a portion 11 of thehousing of the handheld unit of an optical test instrument (e.g.,handheld unit 10 of optical test instrument 1 shown in FIG. 1) isdepicted. In the depicted embodiment, the portion 11 of the housing hasa post 846 and a pair of stops 849, 850 extending downwardly therefromtowards the optical test platform (e.g., optical test platform 800 shownin FIG. 20). The post 846 and stops 849, 850 may each be structured andoperate in substantially the same manner as the post 346 and stops 349,350 detailed above, except that some or all of the post and stops may beattached to the portion 11 of the housing of the handheld unit insteadof the optical test platform. The post and stops may be interchanged,such that a post 846 may be attached to the portion 11 of the housing,while one or more of the stops 349, 350 are attached to the optical testplatform, or vice versa.

Turning to FIGS. 22 and 23, in some embodiments, the cavities 812 a, 812b of the optical test platform 800 may be at least partially defined bya wall 816 a, 816 b of the shell 810. In some embodiments, a wall (e.g.,wall 816 a) may include one or more alignment ribs (e.g., alignment ribs352, 353 shown in FIG. 18). With continued reference to FIGS. 22 and 23,in some embodiments, the wall 816 a may be taller in certain positionsthan in others. For example, the wall 816 a shown in FIGS. 22 and 23 istaller in an area adjacent to the third window 806 and third mount 824than in an area adjacent to the first window 802 and first mount 820.With reference to FIG. 22, the wall 816 a may define a first, tallerheight from the slot 880 (configured to receive a switch therein fordetecting the sample tubes, such as by a mechanical switch) to secondwindow 804, including the third window 806; and the wall 816 a maydefine a second, shorter height from the second window 804 back aroundto the slot 880, including the first window 802.

In some embodiments, the portion of the wall 816 a against which thesample tube (e.g., sample tube 342 shown in FIG. 18) is forced is tallerthan the portion of the wall adjacent the spring (e.g., spring 340 shownin FIG. 18 and/or spring 840 shown in FIG. 20).

The ribs (e.g., alignment ribs 352, 353 shown in FIG. 18) may bepositioned on the first, taller portion of the wall and the spring 840may be positioned above the second, shorter portion of the wall (e.g.,as shown in FIG. 20). In such embodiments, the spring 840 may bepositioned in line with the ribs on a generally horizontal planerelative to the optical test platform 800, such that the line of actionof the spring is directed at the alignment ribs.

With reference to FIGS. 20 and 22-24, the shell 810 may include guidesurfaces 868 having a curved portion 869 and straight portions 870configured to align and hold the sample tubes (e.g., sample tube 342shown in FIG. 17) within the cavities 812 a, 812 b. In the depictedembodiment, the guide surfaces 868 are positioned in both cavities 812a, 812 b and are each shaped as U-channels. The depicted guide surface868 in the cavity 812 a with windows 802, 804, 806, 808 is orientedtowards the third window 806 such that the guide surface 868 cooperateswith the spring 840 and alignment ribs to hold the sample tubevertically in a repeatable, consistent position as described above. Theguide surface 868 may taper downwardly and inwardly from a plane or axison the wall 816 a of the cavity 812 a towards the window 808, such thatthe base of the sample tube is guided towards the repeatable, consistentpredetermined position as it is inserted.

In some embodiments, the lower window 808 may define a complementaryshape to the lower portion of the cavity 812 a. With reference to FIGS.22-24 and 27-28, the lower window 808 may be substantially “U” or “bell”shaped to match the shape of the wall 816 a and guide surfaces 868 ofthe cavity 812 a. The lower window 808 may include a raised edge 809configured to engage the wall 816 a. With reference to FIG. 23, thelower window 808 may be enclosed by and firmly fixed to the shell 810(e.g., by overmolding) at the bottom of the cavity 812 a. With referenceto FIG. 24, in some embodiments, a lower aperture 830 through which theillumination light is transmitted may be substantially circular (e.g.,similar to the aperture 130 described herein). The lower aperture 830may define a radial center at substantially the horizontal center of thecavity 812 a.

With reference to FIGS. 22-24 and 26, in some embodiments, the upperwindows 802, 804, 806 may be substantially square and may not extend thefull height of the cavity 812 a or the channels in which they areseated. The windows 802, 804, 806 may be engaged with the shell 810according to any of the embodiments disclosed herein. In someembodiments, at least a portion of the windows 802, 804, 806 may beshorter than the second, shorter height of the wall 816a discussedabove, such that the spring 840 may operate over the windows. The upperwindows 802, 804, 806 may be embedded in the shell 810 (e.g., viaovermolding), slid into the shell (e.g., vertically downward intopredefined channels), or attached via any other means.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseembodiments of the invention pertain having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is to be understood that the embodiments of the inventionare not to be limited to the specific embodiments disclosed and thatmodifications and other embodiments are intended to be included withinthe scope of the appended claims. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation. Unless otherwise noted, the components andfunctionality of various embodiments of the optical test platform,including the first and second embodiments, may be substantivelyinterchangeable, and unless otherwise noted, the features of oneembodiment are the same as each other embodiment. Any individual featureor functionality and any assembly of components may be substitutedbetween the embodiments disclosed herein without departing from thescope of this disclosure. For example, the spring 340; rollers 354, 355;post 346; alignment ribs 352, 353; and/or stops 350, 351 shown in one ormore of FIGS. 17-19 may individually, collectively, or partiallycollectively be incorporated into the embodiments of FIGS. 1-16 or FIGS.20-28. As another non-limiting example, the guide surfaces 868; thespring 840; the post 846; one or more of the stops 849, 850; the upperwindows 802, 804, 806; the wall 816 a; and/or the lower window 808 mayindividually, collectively, or partially collectively be incorporatedinto the embodiments of FIGS. 1-19.

1.-23. (canceled)
 24. An apparatus for facilitating the opticalinterrogation of a test sample, the test platform comprising: a shelldefining: a cavity for receiving at least a portion of a sample tube;and a pair of apertures, wherein each aperture in the pair of aperturesis configured to optically couple the cavity with an exterior of theshell; a pair of windows each of which is disposed across a respectiveone of the pair of apertures, wherein the pair of windows aresubstantially perpendicular to one another.
 25. The apparatus accordingto claim 24, wherein the shell further defines: a sealed distal end; anda proximal end opposite the sealed distal, the proximal end defining anopening configured to removably receive the portion of the sample tubetherethrough.
 26. The apparatus according to claim 24, furthercomprising an emitter disposed outside the cavity, the emitterconfigured to emit electromagnetic radiation through a first window ofthe pair of windows disposed across a first aperture of the pair ofapertures and into the cavity.
 27. The apparatus according to claim 26,further comprising a second detector disposed outside the cavity, thesecond detector configured to receive a portion of the electromagneticradiation through a third window of the pair of windows disposed acrossa third aperture of the pair of apertures from the cavity.
 28. Theapparatus according to claim 27, wherein the second detector comprises anephelometric sensor.
 29. The apparatus according to claim 27, whereinthe shell further comprises a second aperture, and wherein the testplatform further comprises: a second window disposed across the secondaperture; and a first detector disposed outside the cavity, the firstdetector configured to receive a portion of the electromagneticradiation through the second window, wherein the first window and thesecond window are aligned opposite each other relative to the cavity.30. The apparatus according to claim 27, wherein the shell furthercomprises a fourth aperture, and wherein the test platform furthercomprises: a fourth window disposed across the fourth aperture, whereinthe fourth window is defined at a sealed distal end of the shell andfaces a proximal end opposite the sealed distal end, and wherein thefourth window is substantially perpendicular to the first window and thethird window.
 31. The apparatus according to claim 30, furthercomprising an illumination light disposed outside the cavity, theillumination light configured to emit electromagnetic radiation throughthe fourth window into the cavity and out an opening at the proximal endof the shell.
 32. The apparatus according to claim 31, wherein the shellfurther comprises a second aperture, and wherein the test platformfurther comprises: a second window disposed across the second aperture;and a first detector disposed outside the cavity, the first detectorconfigured to receive a portion of the electromagnetic radiation throughthe second window, wherein the first window and the second window arealigned opposite each other relative to the cavity.
 33. The apparatusaccording to claim 32, wherein the first window, the second window, andthe third window each intersect a plane that is perpendicular to an axisextending from an opening at the proximal end of the shell to the fourthwindow.
 34. The apparatus according to claim 24, further comprising: anillumination light disposed outside the cavity, the illumination lightconfigured to emit electromagnetic radiation through a fourth window ofthe pair of windows disposed across a fourth aperture of the pair ofapertures into the cavity and out an opening at a proximal end of theshell; and a first detector disposed outside the cavity, the firstdetector optically coupled with a second window of the pair of windowsdisposed across a second aperture of the pair of apertures from thecavity.
 35. The apparatus according to claim 24, further comprising: afirst detector disposed outside the cavity, the first detector opticallycoupled with a second window of the pair of windows disposed across asecond aperture of the pair of apertures from the cavity; and a seconddetector disposed outside the cavity, the second detector opticallycoupled with a third window of the pair of windows disposed across athird aperture of the pair of apertures from the cavity.
 36. Theapparatus according to claim 25, further comprising a spring configuredto apply a force on the sample tube in the instance in which the cavityreceives the portion of the sample tube, wherein the force is appliedperpendicular to an axis extending between the sealed distal end and theproximal end.
 37. The apparatus according to claim 36, wherein the shellfurther comprises at least two alignment ribs between the sealed distalend and the proximal end, wherein the alignment ribs are configured toengage the sample tube in an instance in which the cavity receives theportion of the sample tube and position the sample tub relative to thepair of windows, and wherein the force is configured to be applied in adirection that is at least partially towards a point between a firstalignment rib and a second alignment rib of the at least two alignmentribs.
 38. The apparatus according to claim 36, further comprising aroller disposed about a leg of the spring, such that the roller isconfigured to rotate about the leg of the spring in an instance in whichthe sample tube is being inserted into the cavity and/or removed fromthe cavity.
 39. The apparatus according to claim 25, further comprisinga spring configured to apply a net force on the sample tube in theinstance in which the cavity receives the portion of the sample tube,the spring comprising a first leg and a second leg configured to applythe net force on a sample tube towards a point between the first leg andthe second leg.
 40. The apparatus according to claim 39, wherein theshell further comprises at least two alignment ribs between the sealeddistal end and the proximal end, wherein the alignment ribs areconfigured to engage the sample tube in an instance in which the cavityreceives the portion of the sample tube and position the sample tubrelative to the pair of windows, and wherein the net force is configuredto be applied in a direction that is at least partially towards a pointbetween a first alignment rib and a second alignment rib of the at leasttwo alignment ribs.
 41. The apparatus according to claim 39, furthercomprising a first roller disposed about the first leg of the spring anda second roller disposed about the second leg of the spring, such thatthe first roller and the second roller are configured to respectivelyrotate about the first leg and the second leg of the spring in aninstance in which the sample tube is being inserted into the cavityand/or removed from the cavity.
 42. The apparatus according to claim 24,further comprising a first mount for a first optical component and asecond mount for a second optical component, wherein the first mount isdisposed about one of the apertures of the pair of apertures andoptically coupled with the cavity via the one of the apertures, whereinthe second mount is disposed about the other of the apertures of thepair of apertures at the exterior of the shell and optically coupledwith the cavity via the other of the apertures, wherein the first mountis configured to position the first optical component relative a windowof the pair of windows disposed across the respective aperture, whereinthe second mount is configured to position the second optical componentrelative a window of the pair of windows disposed across the respectiveaperture.
 43. The apparatus according to claim 42, wherein the firstmount and the second mount are molded integrally with the shell, andwherein the first mount is configured to shield a sensing portion of thefirst optical component from electromagnetic radiation from directionsother than via the one of the apertures.